1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, which are provided with a piezoelectric element which has a piezoelectric layer and an electrode through which a voltage is applied to the piezoelectric layer, and a piezoelectric element.
2. Related Art
As a piezoelectric actuator which is used in a liquid ejecting head, a piezoelectric element is used which is configured by a piezoelectric material which exhibits an electromechanical conversion function, for example, a piezoelectric layer formed from a crystalline dielectric material, being interposed between two electrodes. As a representative example of a liquid ejecting head, for example, there is an ink jet recording head where a portion of a pressure generating chamber which communicates with a nozzle opening which discharges ink droplets is configured of a vibrating plate and ink droplets are discharged from the nozzle opening by pressure being applied to the ink in the pressure chamber due to the vibrating plate being deformed by the piezoelectric element.
Strong piezoelectric characteristics are demanded in the piezoelectric material which is used as the piezoelectric layer (piezoelectric ceramics) which configures the piezoelectric element in this manner, and as a representative example, there is lead zirconate titanate (PZT) (refer to JP-A-2001-223404).
However, from a point of view of environmental problems, a piezoelectric material, where the amount of lead contained is suppressed, is being demanded. As a piezoelectric material which does not contain lead, for example, there are BiFeO3 and the like which have a perovskite structure expressed by ABO3. Here, the A and B in ABO3 indicate an A site and a B site and are sites where oxygen has a coordination number of 12 and a coordination number of 6 respectively. However, there is a problem that with the BiFeO3-based piezoelectric material, insulation is low and leak currents are easily generated. When leak currents are easily generated, there is a problem that it is difficult to use in the liquid ejecting head since a problem tends to occur such as cracks being easily generated in particular when used in a state where high voltages are applied. As such, in the piezoelectric material used in the piezoelectric element, high insulation of 1×10−3 A/cm2 or less is demanded, for example, during application of 25 V which is a representative driving voltage.
Here, the problems such as these do not only exist in the ink jet recording heads, but of course, also in the same manner in other liquid ejecting heads which discharge liquid droplets other than ink, and also exist in the same manner in piezoelectric elements which are not used in liquid ejecting heads. Furthermore, the problem of leak currents occurs as a serious problem in the form of increased energy consumption when the piezoelectric element is used as a sensor. For example, it is preferable that leak currents also be low in piezoelectric elements which are used in piezoelectric sensors, infrared sensors, heat sensors, and pyroelectric sensors which are used with an applied voltage of 1 V or less.